Electrode and method of making same



y 8; 1945. J. B. BRENNAN 2,375,211

ELECTRODE AND METHODS OF MAKING SAME Filed Aug. 29, 1938 2 Sheets-Sheetl IIIIIIIIm llluflll im Egg: 5 I, 0

1 N VENT OR JOSEPH B- .F/PE/V/VA IV ATTORNEYS y 3, 1945- J. B. BRENNAN2,375,211

ELECTRODE AND METHODS OF MAKING SAME Filed Aug. 29, 1938 2 Sheets-Sheet2 INVENTOR.

BY JOsEPHBBEEA/MN 74 r Y 21.13 m? fi m ATTORNEYS Patented May 8, 1945OFFICE 2,375,211 ELECTRODE AND METHOD OF MAKING SAME Joseph BarryBrennan, Euclid, Ohio Application August 29, 1938, Serial No. 227,316

1 31 Claims.

This invention relates to electrodes or plates for various electricaldevices such as condensers. rectifiers, lightning arrestors, batteriesand the like and more particularly relates to electrodes or plateshaving active surfaces. of spray deposited material. This application ia continuation in part of my copending application Serial No. 158,105,filed August 9, 1937, now Patent No. 2,280,789, issued April 28, 1942.The invention will be described herein with particular reference toelectrolytic condensers having electrode surfaces of spray depositedaluminum or other film forming metal, but it is to be understood thatthe invention is not limited to the particular embodiment described asit may be applied to various other electrical devices.

Electrodes or plates comprising finely divided, conductive, metallicparticles deposited on a suitable base have, as noted in my aforesaidapplication and in my Patent No. 2,104,018 many advantages whenincorporated in various electrical devices, particularly electrolyticcondensers of the type embodying one or more electrodes provided with adielectric film. These advantages principally flow from the fact thatthe effective area of the finely divided particles is very great ascompared with the plane or directly measurable area of the base on whichthey are deposited. The present invention constitutes, in some respects,an improvement upon the inventions disclosed and claimed in my saidpatent and application and one of the objects of this invention is toprovide a more eflicient electrode or plate of the type having a surfacecomposed of minute conductive particles.

Another object is to provide such an electrode in which the conductivityof the spray-deposited layer is increased as compared to prior types ofsprayed electrodes. Another object is to provide efficient andeconomical methods of making such electrodes. Another object is theprovision of a condenser embodying such electrodes. A further object isthe provision of a method of increasing the flexibility and strength ofelectrodes embodying or consisting of spray-deposited metallic layers.Another object is to provide an electrode or plate having a base ofinsulating or poorly conductive material and a conductive layer thereonhaving low resistance which will result in sub stantially uniformcurrent density over its entire area when in use. A further object is toincrease the adhesion of the spray deposited layer to the base. Anotherobject is to provide a method of producing highly conductive paths inthe sprayed surface of an electrode. A further object is to provideefficient and economical terminal constructions for electrodes havingsprayed surfaces.

Further objects and advantages of my invention will become apparent fromthe following description of preferred forms thereof, reference being.made to the accompanying drawings. The essen- Figure 2 is a plan viewof one of the electrodes shown in Figure 1; Figure 3 is a section on anenlarged scale taken along the line 3-3 of Fi ure 2; Figure 4 is afragmentary illustration of an electrode generally similar to that shownin Figure 2. but embodying a slightly different terminal construction;Figure 5 is similar to Figure 4, but shows a further modification of theterminal construction; Figure 6 is a vertical section showing a wet typecondenser embodying my invention; Figure 7 is a transverse sectionthrough the condenser shown in Figure 6 as indicated by the line 'l-i onFigure 6; Figure 8 is a plan view of one type of anode suitable for thecondenser shown in Figure 6; Figure 9 is a view similar to Figure 8 butshowing a modified type of electrode; Figure 10 illustrates a furthermodification; Figure 11 is a sectional view as indicated by the lineil-H on Figure 10; Figure 12 illustrates another modified form ofelectrode; and Figure 13 is a section as indicated by the line i3-|3 onFigure 12.

As shown in Figure 1, a dry type of condenser made according to myinvention may comprise two electrodes 10 separated by spacers H. The

electrodes may be provided with terminal tabs l4 and the whole assemblymay be rolled into cylindrical form as indicated at It and impregnatedwith a suitable film maintaining electrolyte such as that disclosed andclaimed in U. S. Patent No. 2,095,966. The spacers i2, which function toprevent electrical contact between the electrodes I0 and also retain theelectrolyte in their interstices, are preferably formed of strips ofpaper or, as indicated in the drawings, of a woven material such as afabric netting or glass cloth, the material preferably being coated witha suitable material which is insoluble in the electrolyte, as describedand claimed in my application Serial No. 36,182,

filed August 14, 1935, now Patent No. 2,135,492,

issued November 8, 1938.

The electrodes ID are preferably constructed as shown in Figures 2 and 3and consist of a base 20 of any suitable material, for example porous orwoven material such as glass cloth, cotton netting, perforated paper, orwire screening. The

active surfaces 2| of the electrode are preferably for the electrodes.

denser is to beiput one or both of the electrodes may be provided withsprayed layers 2| of aluminum or other film forming metal thefilmforming metal being formed with a dielectric film in any suitablemanner known to those skilled in the art, for example by subjecting theelectrode to electrolysis asan anode in 9. him forming bath such as asolution of borax and boric acid. If the condenser is intended for usein direct current service only one plate need be provided with adielectric film, 'that plate con- 1 stituting the anode of thecondenser. For such a direct current condenser the cathode may consistof aluminum or other fllm forming" metal or, if desired, a non-filmforming metal such as copper may be used. If the condenser is intendedfor alternating current service both electrodes are preferably composedof sprayed film forming metalnnd both are provided with dielectricfilms.

Suchelectrodes, as pointed out in greater detail in my parentapplication No. 158,105 are very advantageous and condensers embodyingmy electrodes have extremely desirable characteristics largely becausethe electrodes have very great -capacities per unit of plane areaandbecause condensers incorporating such electrodes have low resistanceand power factor losses. I have discovered however, that the losses inthe condenser can be further reduced and the characteristics of theelectrodes and plates, and of condensers incorporating the same can beimproved by providing the electrodes with one or more paths or areashaving greater conductivity than the sprayed layers and extending fromthe region where the terminals are connected to the electrodes toregions remote from the terminals. Preferably I form such highlyconductive paths by subjecting the spray deposited layers to heat toweld the sprayed particles in such paths or areas into a compact,substantially integral condition. This may be accomplished, forxample,by flame welding, as by an oxyacetylene torch, by heating thesprayed metal by an electric arc, or by electrical resistance methodssuch as a series of closely spaced spot welds or by passing theelectrode between a pair of electrode rolls engaging opposite sides ofthe electrode and supplying the required welding current and pressure.In carrying out the welding operation by electrical methods, theapparatus employed should preferably be capable of accurate adjustmentso that the current and time of application of the current can becontrolled to produce a weld having the desired characteristics of highconductivity and mechanical strength. The electrodes employed shouldpreferably be formed of materials which will not be deposited on thesurfaces of the welded areas, electrodes of alloys of tungsten carbideand copper being suitable for this purpose. These matters are all withinthe knowledge of those skilled in the welding art.

The effect of such an operation is shown somewhat diagrammatically inthe drawings, lines 22 indicating longitudinally extending conductiveasgmu paths, while the lines 22 and 24 indicate transversely extendingconductive paths one of the lines 22 and the line 24 extending'adiacentto the terminal I of the electrode.

As is shown diagrammatically in Figure 3 the effect of the weldingoperation, particularly if the welding operation is accompanied bypressure as in the case of the electric resistance welding, is

to form the particles in the zone of the weld into a substantiallyintegral mass as indicated for example at 25. When the operation iscarried out on material deposited on a porous base, as shown in thedrawings, the two opposite layers 2| are fused together through theinterstices of the mautilized to its fullest extent further increasingthe efllciency of the device in which the electrode is incorporated.

The conductive paths may be employed with any convenient type ofterminal or tab construction, however, I have found an advantageousconstruction to consist of the metallic tab II which is secured to thesprayed layer 2| by a welding operation as indicated at 21 in Figure 3.As shown diagrammatically in Figure 3 this welding operation not onlymakes an excellent electrical connection and a secure mechanical Jointbetween the tab or terminal and the sprayed surface 2| but also the twosprayed surfaces on opposite sides of the base 20 are fused together asshown at 28 so that a low resistance connection is formed between theterminal and the layer 2|a on the side of the electrode opposite theterminal or tab l4. Even though only one side of the base is providedwith a spray-deposited layer, the'terminal may be welded directlythereto.

A modified form of terminal construction is shown in Figure 4 in whichthe tab 20 consists of a small piece of the same material as the base 20of the electrode having a sprayed coating on both sides, the sprayedcoating on the tab being provided with a highly conductive path 3|produced as described above and the sprayed coatings on the tab and onthe electrode itself being welded together to make the desiredelectrical and mechanical connection between the tab and the sprayedareas 2| of the electrode.

In Figure 5 I have illustrated a very economical type of terminalconstruction which may be employed with the condenser shown in Figure lor in various other types of condensers such as dry condensers embodyinga plurality of flat plates or electrodes, alternate electrodes being ofopposite polarity. In this modification of my invention the base 20 isprovided with a sprayed layer 2| as before and includes the conductivepaths 22 and 24. However, in this form of my invention the terminal forconnecting the electrode to an external circuit is formed merely by asprayed area 32 extending from the main sprayed area 2| toward the edgeof the base ma terial 20. The conductive path 24 is extended throughthis area as indicated at 33 and thus an eilicient electrical connectionto the electrode can be made through the sprayed area 32. When such anelectrode is employed in a paste type of condenser embodying a stack ofelectrodes of alternate polarity, the tabs or sprayed areas 32 may bedisposed on opposite sides. of alternate electrodes to prevent contacttherebetween.

In Figure 6 I have shown my invention as it may be applied to a wet typeof condenser comprising a container for electrolyte 35 constituting thecathode of the condenser and retaining an electrolyte in liquid formindicated at 38 in which the anode 31 is immersed. The anode may beprevented from making contact with the cathode by a spacer 38 and may besupported within the container by a riser or terminal 39 extendingthrough a rubber grommet 40 clamped securely within the depending neckportion 4| of the container. In this type of condenser the electrode mayconsist of any suitable base preferably a flexible fabric or papersprayed on one or both sides with conductive layers 42 of finely dividedfilm forming metal such as aluminum. The riser 39 preferably consists"or an aluminum rod spot welded to the sprayed surface 42 as indicateddiagrammatically at 44. Preferably this electrode also is provided withconductive paths 45 extending longitudinally of the electrode from theend adjacent the riser to the opposite end and produced as describedabove by welding the sprayed particles in the paths together into acompact mass having very low electrical resistance. In this type ofelectrode I preferably employ a plurality of transversely extendingconductive paths or welded areas 81, These paths or areas function not,only to improve the conductivity of the electrode and to uniformlydistribute the current therethrough but also function to strengthen theelectrode so that it can be rigidly supported within the container. Withthis type of construction an electrode consisting of two thin layers ofsprayed material deposited on a fiexible base such as thin cloth orperforated paper can be wound into spiral form and inserted into acontainer to economically produce a wet type condenser having verydesirable electrical characteristics and also having sumcient mechanicalstrength to resist the jolts and jars ordinarily encountered in serviceand in shipment.

In some instances it may be desirable merely to provide the sprayedlayer or layers with :1 number of spots or small areas of increaseddensity and conductivity. Such areas may be conveniently formed by aspot welding machine and function to improve the conductivity of theelectrode and to securely hold the sprayed layers to the base. This typeof construction may be employed with any suitable base material sprayedeither on one or both sides but I find it especially advantageous withthin aluminum foil provided with sprayedlayers on one or both sides.Such an electrode is illustrated in Figure 9 and comprises a base offabric, paper, aluminum foil or other suitable material 50 havingspray-deposited surfaces and preferably provided with perforations i toimprove the circuation of an electrolyte. The spray-deposited layers aresubjected to the spot welding operation in a number of areas asindicated diagrammatically at 52. The riser 39 may be welded to one ofthe sprayed surfaces as at M. This type of construction is especiallyadvantageous in conjunction with electrodes having bases of aluminumfoil because of the improved adherence obtained between the foil and thesprayed layer or layers and the increased flexibility of the sprayedlayers obtained by the welding operation. With this type of constructionthe electrode can be bent into spiral or other shapes without dislodgingthe sprayed layers from the foil.

A further modified form, shown herein as adapted for use in wetcondensers, but also adaptable for dry condensers, is illustrated inFigures 10 and 11. In this modification, the electrode consists of aself-supporting layer of sprayed material 80. To produce this type oflayer a spraydeposit may be deposited upon a moving base formed of amaterial to which the sprayed layer will not adhere such as a metalliccylinder coated with oil or grease, and continuously stripped therefrom.The material is preferably deposited in a layer having greater thicknessthan is usually employed, and the stripped layer is then subjected tothe welding operation to produce areas of greater density and strengthand higher conductivity extending preferably in two directions asindicated by lines 6| and 62. The terminal or riser 39 may be weldeddirectly to the sprayed material as described above and as indicated at44. By this construction an extremely efficient electrode may beeconomically produced, as the electrolyte can penetrate and permeate theporous sprayed material from both sides, and the cost of the basematerial is eliminated.

Under some circumstances it may be desirable to improve the conductivityand strength of the electrode embodying the sprayed layers by welding aconductive metallic strip, wire or rod along the sprayed surface.Further it may be desirable to build up a single electrode by weldingtogether a number of electrodes having sprayed surfaces thus producing aporous mass of film forming material and obtaining an electrode havingvery high capacity in comparison with the volume which it occupies. Bothof these features are illustrated in the electrode shown in Figures 12and 13, but it is to be understood that the features can be usedseparately as well as together.

In this modification of my invention the electrode is shown ascomprising two cloth strips Hi and II each provided with sprayed layerson the opposite sides thereof as indicated at l2, 13, It and 15. Toincrease the conductivity and emciency of the electrode, as well as tostrengthen it, a conductive metallic strip shown in the drawings as apiece of foil 16 may be extended longitudinally of the cloth strips anddisposed between them and welded to the inner sprayed layers 13 and M asindicated diagrammatically at H. Further conductive paths may beprovided by subjecting both strips to simultaneous welding operations asdescribed before to produce welded paths l8 and 19. It is to beunderstood that if desired two or more sprayed strips may be weldedtogether as indicated at 18 and 79 without the use of a conductivemetallic strip and further that the metallic strip may be utilized inconjunction with an electrode comprising a single strip of material, themetallic strip in that case being welded to one of the sprayed surfacesof the electrode.

Preferably electrodes of this type are provided with a number ofperforations as indicated at 80 to assist in the fiow of the electrolytein the condenser and to permit the electrolyte to permeate the assembledelectrode so that all of the film forming area thereof may be usedeifectively.

All of the various types of electrodes described herein may be made ofaluminum or other film forming metal and provided with dielectric filmsas described above if required by the service for which they areintended. Filmed electrodes made according to the various forms of myinvention described herein are especially advantageous because of thegreat eflective area of the film, and because the electrolyte canpenetrate and permeate the spray deposited layers.

By my invention the terminal members for the electrode plates can beeconomically secured to the conductive areas of the plates in a fashionthat insures proper connection between the active surfaces of the platesand the terminals and reduces the electrical resistance ordinarilyencountered at the point of connection between the terminal and suchsprayed areas. My invention further provides electrodes having surfacescomposed of finely divided cohering metallic particles which have lowresistance because of the conductive paths extending therethrough andwhich are extremely efficient in service because the conductivity issuch that the current density throughout the electrodes or plates issubstantially uniform. The compacted, fused, or welded areas or paths,in addition to increasing the conductivity of the sprayed layer, give itadditional mechanical strength, and if a supporting base is employedimprove the adherence of the layer thereto. My invention is useful inconjunction with electrodes or plates having a sprayed metallic surfaceregardless of the materia1 employed as the base on which the sprayedmaterial is deposited. For example, the invention is useful inconnection with electrodes having bases made of rigid materials such asporcelain or glass. Terminal connections for electrodes embodying myinvention may be made rapidly and economically, and the conductive pathsmay be formed at a very low cost as they require only a, simple weldingoperation and involve no additional material.

In the foregoing specification I have described only preferred forms ofmy invention in their application to electrical condensers. However,those skilled in the art will appreciate that my invention may bemodified in various ways, only some of which have been specificallymentioned herein and may be applied to diflerent types of electricaldevices, all without departing from the spirit and scope of myinvention. Therefore it is to be understood that my patent is notlimited to the specific forms described herein or in any manner otherthan by the scope of the appended claims when given the range ofequivalents to which my patent may be entitled.

I claim:

1. An electrode terminal assembly comprising an electrode aving aconductive layer of finely divided metallic particles and a terminal tabcomprising a cloth strip having a conductive layer of metallic particlesdeposited thereon, the conductive layer on said terminal tab beingwelded to the conductive layer of said electrode.

2. An electrode for electrolytic condensers comprising a base ofnon-conducting material having atJeast a portion of the area thereofcoated with a conductive layer of finely divided metallic particles, anda terminal for connecting said electrode to an external circuit, saidelectrode having at least one path of greater conductivity than saidlayer extending from a region adjacentsaid terminal to a region remotefrom said terminal.

3. An electrode for an electrolytic condenser, comprising aspray-deposited layer of finely divided cohering particles of filmforming metal reinforced by areas comprising spray-deposited particlesfused together into substantially integral masses.

4. An electrode for an electrolytic condenser comprising aspray-deposited layer of finely divided cohering particles of filmforming material and a terminal for connecting said electrode to anexternal circuit, there being a path of greater conductivity andstrength extending along said layer, said path being of a lesser areathan said layer.

5. An electrode for electrolytic devices comprising a porous base ofnon-conducting material, a portion of the area of which is coated with aconductive layer of finely divided metallic particles, the particles ina portion of said layer being fused together into a form more dense thanthe remainder of said layer.

6. An electrode for electrolytic condensers comprising a base ofnon-conductive material having at least a portion of the area thereofcoated with a conductive layer of finely divided metallic particles,said electrode having at least one path of greater conductivity thansaid layer extending along said layer and throughout a substantialportion thereof.

7. In an electrolytic condenser, an electrode comprising a fiexibleporous base having at least a portion of the area of both sides thereofcoated with conductive layers of finely divided metallic particles, anda terminal for connecting said electrode to an external circuit, saidelectrode having at least one, path of greater conductivity than saidlayers extending along said electrode from a region adjacent saidterminal to a region remote from said terminal, said path comprisingparticles of said layers welded to each other through the interstices ofsaid porous base.

8. An electrode for electrolytic condensers comprising a base having atleast a portion of the area coated with a conductive layer of finelydivided metallic particles, and a terminal welded to said layer forconnecting said electrode to an external circuit, said electrode havingat least one path of greater conductivity than said layer extending froma region adjacent said terminal to a region remote from said terminal,said path comprising particles of said layer welded to each other into asubstantially integrated mass.

9. An electrode for electrolytic condensers com-.

prising a mesh fabric base having at least a portion of the area of bothsides thereof coated with conductive layers of finely divided metallicparticles, and a terminal for connecting said electrode to an externalcircuit, said electrode having at least one path of greater conductivitythan said layers extending from a region adjacent said terminal to aregion remote from said terminal, said path comprising particles of saidlayers welded to each other through the interstices of said fabric base.

10. An electrode for electrolytic condensers comprising a flexibleporous base having a portion of the area of both sides thereof coatedwith a conductive layer of finely divided metallic particles, a terminalfor connecting said electrode to an external circuit comprising aconductor weld ed to one of said conductive layers, the other of saidconductive layers being compacted and welded into electrical contactwith the first mentioned of said layers, through the interstices of theporous base in the region of the weld, and at least one path of greaterconductivity than said layers extending from a region adjacent saidterminal to a region remote from said terminal, said path comprisingcompacted particles of said layers welded to each other through theinterstices of said porous base.

11. An electrode or plate comprising at least two separately formed,juxtaposed layers of finely divided cohering metallic particles, and ametallic conductor disposed between said layers and welded thereto.

12. An electrode comprising a layer of finely divided metallic particleshaving a terminal, and a metallic conductor extending along said layerand welded thereto.

13. An electrode or plate comprising a plurality of strips of flexiblebase material each having a spray-deposited layer of finely dividedmetallic particles thereon, the spray deposited layer on one strip beingwelded to the spray deposited layer on an adjacent strip.

14. The method of making electrodes or plates which includes the stepsof producing a spraydeposited layer of finely divided cohering metallicparticles and thereafter providing said layer with a path of increasedstrength and conductivity by welding together the particles in saidpath.

15. The method of making electrodes or plates which includes the stepsof spraying finely divided particles of molten metal upon a base,removing the deposited layer from the base, and fusing the particles ina portion of said layer together.

16. The method of making electrodes orplates which includes the steps ofspraying finely divided particles of molten metal upon a suitable baseto provide a conductive layer of cohering metallic particles, andthereafter subjecting a. narrow area of said layer to additional heat toweld together the particles in such area to produce a narrow path ofgreater conductivity than the remaining portion of said layer.

17. The method of making electrodes or plates which includes the stepsof spraying finely divided particles of molten metal up'on oppositesides of a thin, porous base to provide conductive layers of coheringmetallic particles on both sides thereof, and thereafter subjectingadjacent narrow areas of said layers to heat to weld together theparticles in such areas through the interstices of the base to produce anarrow path of greater conductivity than the remaining portions of saidlayers,

18. An electrode for electrolytic devices comprising a layer of metalcharacterized by a certain ratio of surface area to volume and acontiguous contacting deposit of film-forming metal suspended in an openmesh fibrous normally non-conducting material and characterized by amuch higher ratio of surface area to volume of metal.

19. An electrode for electrolytic condensers comprising at least twolayers of fibrous flexible material disposed in face to face contact anda multiplicity of particles of film-forming metal adhering to the fibersof said layers and an additional metallic conductor between said layersand in electrical contact with the particles of film-forming metal.

20. An electrode for electrolytic condensers comprising at least twolayers of fibrous flexible material disposed in face-to-face contact anda multiplicity of particles of film-forming metal adhering to the fibresof said layers and to each other.

21. An electrode for electrolytic condensers comprising at least twolayers of fibrous flexible material disposed in face-to-fsce contact anda multiplicity of particles of film-forming metal adhering to the fibresof said layers and to each other, said particles also serving to bondsaid layers together.

22. An electrode for electrolytic condensers comprising at least twolayers of fibrous flexible material disposed in i'ace-.-to-i'ace contactand a multiplicity of particles of aluminum adhering to me fibres ofsaid layers and to each other.

23. An electrode for electrolytic condensers comprising at least twolayers or cloth disposed in face-to-face contact and a multiplicity ofparticles of film-forming metal adhering to the fibres of said layersand to each other.

24. An electrode for electrolytic condensers comprising at least twolayers or cloth disposed in Iace-to-face contact and a multiplicity orparticles of film-forming metal adhering to the nor-es of said layersand to each other, said particles also serving to bond said layerstogether.

25. An electrode for electrolytic condensers comprising at least twolayers of fibrous flexible material disposed in face-to-race contact anda mult plicity or particles of him-forming metal adhering to the fibresof said layers and to eacn other and an additional metallic conductorbetween said layers and in contact therewith.

26. An electrode 101 l electrolytic condensers comprising at least twolayers or nbrous flexible material disposed in face-to-i'ace contact anda multiplicity of particles of film-forming metal adhering to the nbresof said layers and to each other and an additional metallic conductorbetween said layers and in contact therewith, said particles alsoserving to bond said layers to said conductor.

27. An electrode for electrolytic condensers comprising a layer offibrous flexible material disposed in face-to-face contact with asupplemental electrode of film-forming metal, and a multiplicity ofparticles of film-forming metal adhering to the fibres or said layer andto each other, said particles also serving to bond said layer to saidsupplemental electrode.

28. A film-forming electrode comprising a layer of cloth disposed inface-to-face contact with a sheet of aluminum, and a multiplicity ofaluminum particles adhering to the fibres of said cloth and to the faceor said sheet, said particles binding said cloth to said sheet.

29. An electrode for electrolytic devices comprising a layer offilm-forming metal characterized by a certain ratio of surface area tovolume and a conti uous contacting deposit of said metal s spended in aloose mesh fibrous non-metallic material and characterized by a muchhigher ratio of surface area to volume of metal, said de- 1ggrsit beingof greater extent than said low ratio 30. An electrode for electrolyticcondensers comprising a spray deposit of film-forming metal on an openmesh fibrous base, said deposit having a porosity greater than theporosity of such a deposit on a continuous solid surface and aconducting layer in intimate contact with said deposit at pointsdistributed over a substantial portion of its surface.

31. An electrode for electrolytic condensers comprising a porouswick-type layer or film- !orming metal on an open mesh fibrous base andcontiguous conductive layer in intimate contact therewith.

JOSEPH BARRY BRENNAN.

